Locking device



' Nov. 28, 1944- o. H. GRISWOLD LOCKING DEVICE 2 Sheefs-Sheet 1 Filed Dec. 28, 1945 INVENTOR Owe h Gr mm/J ATTORNEYS 2 Shets-Sheet 2 ATTORN EY5 4- 0H. GRISWOLD LOCKING DEVICE Filed Dec. 28, 1945 Patented Nov. 28, 1944 Owen Griswold, Trenton, N. J., assignor to vKaiser Cargo, Inc., Bristol, Pa... a corporation of California Application December 2a, 1943, Serial No. 515,922

,4 Claims. (01. 287439) This invention relates to landing gear for airplanes and particularly toimprovements in 1ock ing the hinged members when'the gearisextended. purpose indicated, the invention may be utilized in other structures where asimilar problemof securely locking an elbow joint is met.

In the landing gear of modern airplanes; the wheel supports or struts include pivotally connected sections, the lower of which'is adapted to swing to and from extended position. When Although adapted especially for the the plane is flying, the wheels are withdrawn into recesses provided for that purpose in the 'fuselage. When extended, the struts are often subjected to great tensile and compressive loads and should be securely, locked to prevent inadvertent failure or folding of the struts. Heretofore it has been necessary to rely on latches or pins as locking devices. These are inherentlyweak, are subject to misalignment and slipping, and frequently jam because of accumulation of dirt and other extraneous material. i

It is the object of the present invention to pro, vide a simple and effective device which can be manipulated easily to lock or release the pivotal connection between the parts of'a wheel strut and which avoids the difficulties attendant upon the use of latches for that purpose.

Another object of the invention is the provision of a locking device which, when actuated, effects the desired movement of the lower element of the strut and which is not afiected by foreign matter, is not released by recoil or backlash under tensile or compressive loads, and eliminates necessity for latches or similar holding means.

Other objects and advantages of the invention will be apparent as it is better understood by reference to the following specification and the accompanying drawings, in which Fig. 1 is a view in perspective of the joint with the locking device in looking position;

Fig. 2 is a similar view showing the operation of the joint;

Fig. 3 is a view in perspective showing another phase of the operation;

Fig. 4 is a vertical section through the joint showing the locking device in locking position;

and

Fig. 5 is a transverse section through the joint with the locking device in looking position. Referring to the drawings, 5 indicates the upper portion of a Wheel strut which is secured to a hinge member 6 and articulated by means of pins 1 with abracket 8 to which the lower section of the wheelstrut may be secured. When the members 5 and 8 are turned about the pins 1, the strut is folded as shown in Figs. 2 and 3,

to liftthe wheels from their supporting position to the position in which they are carried while the plane is flying. This movement is efiected in the manner hereinafter described by the actuation of the device which locks the strut against I such movement while it is in extended position.

Toensure efiective locking of-the-joint I providetwo links Band 10 which are supportedon pins H and l 2 on the bracket .8 opposite the pins 1. Thef links 9 andllll are pivotally connected by a pin l3 to a bifurcated link 14 which is of greater length than the links 9 and Ill. The opposite end of the link I4 is pivotally connected by a pin IE to a lug I6 secured to the hinge memher 6. A rod." is pivotally connectedat I8 to i the link I4, and the latter may be actuated.

through therod to effect movement of the links 9. and Ill and of the bracket 8. The rod I! may be actuated by any suitable power mechanism such as a hydraulic motor (not shown).

When the axes of the upper portion 5 of the wheel strut and the bracket 8 are in alignment, the links 9, I0 and [4 are in looking position, as

indicated in Figs. 1, 4 and 5. In this position,-

the links. are in alignment and' hencethe strut is securely locked against movement about the pins 1. No tensile or compressive stress can efiect the breaking of the joint so long as the links 9, I0 and M are held in this position. Hence, until the rod I1 is actuated, no movement of the parts can occur.

When movement is to be effected for the purpose of raising the wheels, the rod H is actuated through the mechanism provided for that purpose. The link l4 begins to swing upwardly, carrying with it the links 9 and I0. This movement immediately breaks the lock and simultaneously moves the bracket 8 pivotally about the pins I3 and the movement continues until the bracket has,

been carried to its uppermost position as shown in Fig. 3, where it is held until the rod I1 is actuated in the opposite direction toreturn the bracket to its original position with the links 9, l0 and I4 again in alignment to securely lock the joint The movement of the bracket 8 is assured by reason of the difference in length between the link 14 and the links 9 and I0. Hence the bracket must move in the manner indicated whenever these links are swungfrom' the position in which they are in alignment and lock the joint.

The structure as described has numerous advantages. All of themovement occurs about the and hence, difliculty in engagement when required. Furthermore the structure is much stronger with a given weight than any possible latch structure, and its operation is positive so that there can be no mishap through failure of a part to properly. engage or disengage when required. When the parts are in locking position, there is no possibility of turning the two sections of the strut about their pivotal axis. The release and movement of the strut are nevertheless ef fected' by a single operationof the hydraulic mo-' tor or other power mechanism employed to lift the wheels. v I v ,Various changes may. be madein the form and arrangement of the parts as well as inthe utilization or the lockingdevice for other than itsprimary purpose without departing from the inventionor sacrificing the advantagesthereof.

I claim: i I I 1. In an articulated joint, thecombination oi pivotally connected members, a locking device comprising pivotally connected links eachtpivo-tally mounted respectively on one of the members and adapted wheniin alignment to lock the joint, one ofthe, links being longer than theother link whereby when the links are actuated the members are caused to move about their pivotal axis, and means for actuating the links.

2. In an articulated joint, the combination of pivotally connected members, a locking device comprising a pair of links pivoted on one of the members, a longer link pivotally connected to the pair of links and to the other member, the links when in alignment beingadapted to lock the joint, and means for actuating the links whereby the members are caused to move about their pivotal axis.

3. In an airplane wheel strut, the combination of pivotally connected strut members adapted when aligned to sustain tensile and compressive loads, a locking device comprising pivotally connected links each pivotally mounted respectively on one of the members and adapted when in alignment to lock the joint, one of the links being longer than the other link whereby when the links are actuated the members are caused to move about their pivotal axis and means for actuating thelinks.

4.. Inan airplane wheel strut, the combination of pivotally connected strut members adapted when aligned to sustain tensile and compressive loads, a locking device comprising a pair of linlm pivoted onone of the members, a longer link pivotally connected to the pair of links and to the other member, the links when in alignment being adapted to lock the joint, and means for actuatingthe links whereby the members are caused to move about their pivotal OWEN H. GRISWOLDP 

